Hollow-fiber spinning nozzle

ABSTRACT

A hollow fiber spinning nozzle in which supply bores and a nozzle structure connected to these and having a mass discharge opening and a needle with a coagulation agent bore are formed in a base body. At least two plate-shaped bodies structured by means of micro-structure technology are joined together to form the base body.

This is a nationalization of PCT/EP03/01447 filed Feb. 13, 2003 andpublished in German.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a hollow fiber spinning nozzle in whichcoagulation agent/support agent passages and mass supply passages and anozzle structure connected to these and having a mass discharge openingand a needle with a coagulation agent/support agent bore are formed in abase body.

2. Description of the Related Art

Hollow fiber spinning nozzles are already known which serve themanufacture of polymeric hollow fiber membranes. As shown in FIG. 1 inaccordance with the enclosed drawing, such hollow fiber spinning nozzles10 consist of a base body 12 made of metal into which a plurality ofbores 14, 16, 18, 22 have been introduced. A tube 20 has been fittedinto the bore 14 and a coagulation agent passage or a support agentpassage 22 has been formed therein for the introduction of thecoagulation agent or support agent. The bores 16 and 18 form mass supplypassages for a polymer which is discharged via a ring passage 22 whichlikewise consists of a corresponding bore. Methods of customary metalworking are used in the manufacture of the known hollow fiber spinningnozzles 10. It is here therefore that the nozzle structure arises by theassembly of both nozzle parts, with any irregularity, for example in thegeometry of the ring space 22 totalizing from the production errors onthe production of the base body 12 and the tube 20. Furthermore,possible assembly errors also occur which can likewise result in anirregularity of the geometry. Finally, the hollow fiber spinning nozzlesknown from the prior art cannot be reduced to any desired size.

SUMMARY OF THE INVENTION.

It is therefore the object of the invention to provide hollow fiberspinning nozzles with which fine capillary membranes can also bemanufactured, with the production tolerances being minimized and themanufacturing process for these hollow fiber spinning nozzles being mademuch cheaper.

This object is solved in accordance with the present invention which isdirected to a hollow fiber spinning nozzle in which coagulationagent/support agent passages and mass supply passages and a nozzlestructure connected to these and having a mass discharge opening and aneedle with a coagulation agent/support agent bore are formed in a basebody which is constructed by the joining together of at least twoplate-shaped bodies structured by means of microstructure technology. Acompletely innovative manner of construction is thus provided for hollowfiber spinning nozzles, since the invention moves away from conventionalmetal working and uses methods of microstructure technology. Inaccordance with the invention, at least two plate-shaped bodiesstructured by means of microstructure technology are namely assembled toform the hollow fiber spinning nozzle. A second non-structured plate ispreferably joined onto a first plate formed by means of microstructuretechnology in this process, with the second plate only being structuredafter attachment to the first plate. The plates are are really connectedto one another. A plurality of advantages are opened up by the newproduction method. First, a substantially smaller dimensioning of thenozzle structure can be realized by means of microstructure technology.Moreover, a substantially higher precision can be realized with respectto the nozzle structure. This precision comes about in that the nozzlestructure arises in one step. It is only restricted by the precision ofthe underlying lithography mask which is used in microstructuretechnology. Such lithography masks can, however, be produced extremelyprecisely with tolerances of 100 nm. A further advantage of the methodin accordance with the invention lies in the substantially lowerproduction costs of the spinning nozzles. Special aspects of theinvention are summarized in the following paragraphs.

Generally, all materials of microstructure technology can naturally beused for the realization of the hollow fiber spinning nozzles inaccordance with the invention, provided they can be anisotropicallyetched and bonded. However, mono-crystalline silicon, gallium arsenide(GaAs) or germanium can particularly advantageously be used.

In accordance with a particular embodiment of the invention, a hollowfiber spinning nozzle consists of two plates, with the mass supplypassages, a mass flow homogenization zone, a coagulation agent/supportagent supply bore and a needle stub being cut out in the first plate,while a nozzle structure having a mass annular gap and a needle with acoagulation agent/support agent bore being cut out in the second plate.

Alternatively, a design is also feasible in which the second plateadditionally contains the mass supply passages and the mass flowhomogenization zone. These elements and the needle stub are omitted onthe first plate there. A particular feature of this design is that theneedle of the spinning nozzle is only connected to the first plate at anend face.

These preferred aspects for a hollow fiber spinning nozzle, with which asimple capillary hollow fiber membrane can be manufactured,advantageously have the following dimensions:

Thickness of the first plate: 0.250-1.500 mm Thickness of the secondplate: 0.050-1.500 mm Outer diameter of the needle: 0.020-1.500 mmLength of the needle, incl. needle stub: 0.100-2.000 mm Diameter of thecoagulation agent bore: 0.010-1.000 mm Length of the coagulation agentbore: 0.150-2.500 mm Outer diameter of the annular gap: 0.040-3.000 mmLength of the annular gap: 0.050-1.500 mm Height of the spinning nozzle:0.300-3.000 mm Edge length of the spinning nozzle: 1.000-25.00 mm.

A further preferred aspect of the invention consists of three plates,with the first plate including supply passages, a homogenization zoneand a needle stub with a central supply bore, a second plate whichadjoins the first plate has supply passages, a homogenization zone and afurther needle stub with a concentric ring passage and a needleextension, and wherein a third plate which in turn adjoins the secondplate has a nozzle structure consisting of a central bore and twoconcentric annular gaps. Capillary membranes with co-extruded doublelayers can be manufactured by means of this hollow fiber spinning nozzlein accordance with the invention.

An alternative embodiment results in that the hollow fiber spinningnozzle is made up of three single plates, with the first plate having acentral supply bore, a second plate adjoining the first plate havingparallel supply passages and homogenization zones arranged with respectto these as well as a needle stub with a concentric ring passage and acentral bore and with the third plate adjoining the second plate havinga nozzle structure consisting of a central bore and two concentricannular gaps.

The outer diameter of the multi-passage hollow fiber spinning nozzle isadvantageously smaller than 1 mm. The outer diameter of themulti-passage hollow fiber spinning nozzle is particularlyadvantageously smaller than or equal to 0.45 mm. A dialysis membranewith an inner diameter of 200-300 μm can be manufactured with this.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages of the invention result from theembodiments shown in the drawings.

FIG. 1 is a schematic section through a hollow fiber spinning nozzle inaccordance with an embodiment in accordance with the prior art.

FIG. 2 is a schematic section through a hollow fiber spinning nozzle inaccordance with a first aspect of the invention.

FIG. 3 a is a schematic sectional representation of a hollow fiberspinning nozzle in accordance with a second embodiment of the invention,showing a first of three variants of the arrangement of the mass supplypassages.

FIG. 3 b is another schematic sectional representation of a hollow fiberspinning nozzle in accordance with the second embodiment of theinvention, showing a second of three variants of the arrangement of themass supply passages.

FIG. 3 c is a further schematic sectional representation of a hollowfiber spinning nozzle in accordance with the second embodiment of theinvention, showing the third of three variants of the arrangement of themass supply passages.

FIG. 4 is a partly sectioned three-dimensional representation of ahollow fiber spinning nozzle in accordance with FIG. 2.

FIG. 5 is a partly sectioned three-dimensional representation of ahollow fiber spinning nozzle in accordance with the embodiment of FIG. 3a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

In FIG. 2, a hollow fiber spinning nozzle 10 in accordance with a firstaspect of the invention is shown. Here, the total base body 26 is puttogether from two single plates 30 and 32. In the first plate 30, masssupply passages 34, a mass flow homogenization zone 36, a coagulationagent supply bore 38 and a needle stub 40 are formed by a correspondingetching process which will be described in detail later. Thethree-dimensional design of the hollow fiber spinning nozzle shown herein FIG. 2 results from FIG. 4. It can be seen there that the mass supplypassages, i.e. the passages for the supply of the polymeric mass to beprecipitated, are arranged in cross shape in the embodiment shown here.The mass flow homogenization zone 36 results as a ring space around theneedle stub 40. The coagulation agent supply bore 38 is broadened in itsregion pointing toward the upper side, as can in particular be seen fromFIG. 2.

The design of the second plate 32 can also be seen from FIGS. 2 and 4which has a mass discharge opening 42 which directly adjoins the massflow homogenization zone 36. This mass discharge opening or the massannular gap 42 results, with the needle 44 with coagulation agent bore46, in the high-precision nozzle structure 48. The embodiment shown inFIGS. 2 and 4 of mono-crystalline silicon has, for example, a thicknessof the first plate of 0.4 mm, a thickness of the second plate of 0.1 mm,an outer diameter of the needle of 0.05 mm, a length of the needleincluding the needle stub of 0.15 mm, a diameter of the coagulationagent bore 38 in the expanded region of 0.1 mm, an outer diameter of theannular gap 42 of 0.1 mm and a length of the annular gap 42 of 0.1 mm.The height of the base body 26, i.e. the height of the total spinningnozzle 10, accordingly amounts to 0.5 mm, while an edge length of thebase body 26 of the spinning nozzle 10 amounts to 2 mm.

In the manufacture of hollow fiber spinning nozzles by means ofmicrostructure technology, 2 round wafer disks with diameters of 100 to300 mm are the starting point. A plurality of spinning nozzle structuresare simultaneously made from these wafers. The individual hollow fiberspinning nozzles 10 are then obtained by dividing the wafers alreadyprocessed. The individual split spinning nozzles can each be given asingle nozzle structure, as shown here, or also a plurality of nozzlestructures in one nozzle structure compound. This is achieved in thatnot all nozzle structures formed on the wafer are separated from oneanother, but that a plurality of nozzle structures together form onemulti-nozzle unit which are cut out from the wafer along their outercontour.

The manufacture of the spinning nozzles 10 starts with the two-sidestructuring of a first wafer which accommodates the elements 34, 36, 38,40 of the plate 30 of the spinning nozzle 10. The structures areproduced with a sequence of standard lithography processes, i.e. masksof photoresist, SiO, Si—N or similar, and standard etching processes. Inthe standard etching processes, in particular reactive ion etching(RIE), deep reactive ion etching (DRIE) and cryo-etching should benamed. Specific deep etching processes such as DRIE and cryo-etching areparticularly suitable. The lithography masks for the front side and forthe rear side must be optically aligned to one another. Subsequently,the second wafer, from which the second plate should be manufactured, isbonded to the correspondingly structured first wafer. In this process,all bonding methods can be used, anodic bonding, direct bonding orsimilar.

However, direct bonding is particularly suitable since the higheststrengths are reached and thus a good hold of the needle on the firstplate is ensured. In the next step, the nozzle structure 48 with theannular gap 42 and the coagulation agent bore 46 are manufactured in atwo-stage etching process. In the first step, only the deepercoagulation agent bore is driven forward. In the second step, bothstructures are then etch finished. Said lithography processes andetching processes area again used, with the use of the deep etchingprocess being more advisable here than in the working of the firstwafer. In the final step, the individual spinning nozzles are, asalready previously described, cut out of the wafer by suitableseparation processes such as wafer sawing or laser working.

Further alternative aspects of the invention will be explained withreference to FIGS. 3 and 5. Here, a hollow fiber spinning nozzle 10 isshown for the manufacture of a hollow fiber co-extruded from two layers.Here, a hollow fiber spinning nozzle 10 is shown with a base body 100consisting of three single plates 102, 104 and 106. The single plates inturn consist of mono-crystalline silicon. A supply passage 108 for thecoagulation agent is cut out in the first plate. In addition, supplypassages 110, 112 for a first polymer are provided which open into anassociated homogenization zone 114. The homogenization zone 114surrounds a corresponding needle stub 116.

A coagulation agent bore 118 is likewise cut out in the second plate 104and is surrounded by a further needle stub 120 and by a ring space 122.Furthermore, further supply passages 124 are cut out in the second plate104 with a subsequent homogenization zone 126. Finally, the third plate106 has two annular gaps 128 and 130 for the respective polymericmaterials which should be co-extruded as well as a needle 132 with acoagulation agent bore 134. In the variants of FIG. 3 a, FIG. 3 b andFIG. 3 c, the supply passages 124 are each designed differently. Whilethe supply passage 124 for the second polymer is only provided in thesecond plate 104 in the embodiment in accordance with FIG. 3 a, itextends in the variant in accordance with FIG. 3 b both through thesecond plate 104 and through the third plate 106. In the embodiment inaccordance with FIG. 3 c, the supply passage 124 for the second polymerextends through the second plate 104 and the first plate 102, as shownhere in FIG. 3 c. The representation in accordance with FIG. 5corresponds to the section in accordance with FIG. 3 a, with it becomingclear here that 8 supply passages 112 are arranged in star shape, whileonly 4 supply passages 124 are arranged in cross shape.

The three plates 102, 104 and 106 are in turn connected to one anotherto form the base body 100 by a suitable bonding process, advantageouslyby direct bonding. Otherwise, the manufacturing method for the hollowfiber spinning nozzle 10 in accordance with FIGS. 3 and 5 correspondsanalogously to that as was already explained in detail with reference toFIGS. 2 and 4.

The invention being thus described, it will be apparent that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be recognized by one skilled in the art areintended to be included within the scope of the following claims.

1. A hollow fiber spinning nozzle comprising three plates, with thefirst plate having supply passages, a homogenization zone and a needlestub with a central supply bore, a second plate which adjoins the firstplate having supply passages, a homogenization zone and a further needlestub with a concentric ring passage as well as a needle extension with acentral bore, and a third plate which adjoins the second plate having anozzle structure including a central bore and two concentric annulargaps.
 2. The hollow fiber spinning nozzle in accordance with claim 1,wherein said nozzle includes mono-crystalline silicon, gallium arsenide(GaAs) or germanium.
 3. The hollow fiber spinning nozzle in accordancewith claim 1, wherein an outer diameter of the hollow fiber spinningnozzle is smaller than 1 mm.
 4. The hollow fiber spinning nozzle inaccordance with claim 1, wherein an outer diameter of the hollow fiberspinning nozzle is smaller than or equal to 0.45 mm.
 5. A hollow fiberspinning nozzle comprising a plurality of plates having a coagulationagent/support agent bore passing therethrough, a first plate having asupply passage and a homogenization zone surrounding said bore, a secondplate adjoining said first plate and having a further supply passagesubstantially parallel with said first plate supply passage and providedwith a further homogenization zone, and a third plate adjoining thesecond plate and having a nozzle structure with two concentric annulargaps.
 6. The hollow fiber spinning nozzle as set forth in claim 5,wherein said first plate homogenization zone is in fluid communicationwith one of said two concentric annular craps via a ring space.
 7. Thehollow fiber spinning nozzle as set forth in claim 6, wherein said ringspace is concentric with said bore in said second plate.
 8. The hollowfiber spinning nozzle as set forth in claim 6, wherein said second plateincludes a further supply passage parallel with said ring space.
 9. Thehollow fiber spinning nozzle as set forth in claim 5, wherein said thirdplate further includes a supply passage substantially in verticalalignment with a portion of the supply passage in said first plate andseparated therefrom by said second plate.
 10. A hollow fiber spinningnozzle comprising: a first plate having a coagulation agent/supportagent passage, a supply passage and a homogenization zone surrounding aneedle stub; a second plate adjoining said first plate and having afurther supply passage, a further homogenization zone and a furtherneedle stub in alignment with said first plate needle stub; and a thirdplate adjoining the second plate and having a nozzle structure includinga central bore in alignment with said needle stubs and two concentricannular gaps.
 11. The hollow fiber spinning nozzle as set forth in claim10, wherein said first homogenization zone is in fluid communicationwith one of said two concentric annular gaps via a ring space.
 12. Thehollow fiber spinning nozzle as set forth in claim 11, wherein said ringspace is concentric with said further needle stub and a central bore ofsaid second plate.
 13. The hollow fiber spinning nozzle as set forth inclaim 11, wherein said supply passage in said second plate is parallelwith said ring space.
 14. The hollow fiber spinning nozzle as set forthin claim 10, wherein said supply passage in said second plate issubstantially parallel with the supply passage in said first plate. 15.The hollow fiber spinning nozzle as set forth in claim 10, wherein saidthird plate further includes a supply passage substantially in verticalalignment with the supply passage in said first plate and separatedtherefrom by said second plate.